There are several different types of analog-to-digital converter (ADC) circuits. One type of ADC circuit is a successive approximation (SA) ADC. A successive approximation ADC tests multiple digital output codes. Typically, the analog input voltage is sampled. Then, the most significant bit of the digital output code is set initially to one, and the remaining bits are initially set to zero. Next, the digital output code is tested. If the digital output code is too low, the most significant bit is left at one. Alternatively, if the digital output code is too high, the bit is changed to zero. Then, the second most significant bit is changed to one. The digital output code is tested again. If the digital output code is too low, the second most significant bit is left at one. Alternatively, if the digital output code is too high, the second most significant bit is changed back to zero. The process is repeated until all of the bits have been tested.